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I used to be an electrician many years ago (trained by the USCG, worked commercial/residential at EOE). Is been about 13 years since I wired up a service panel. I am building a new home and need a little guidance on purchasing and wiring the correct service panel.

The home will be a little over 4300 square feet in size. With 2 furnaces and possibly 2 A/C's as well. I am planning on a 400-amp service feeding 2-200 amp sub-panels in the house. I would like to have some distribution on the outside of the home in order to feed future landscape lighting in the backyard as well as a small sub-panel for a shop.

Would a metered panel that has two 200-amp breakers in it and distribution work to feed the inside sub-panels as well? (e.g. HP816P400BS ). I am assuming that the factory installed 200-amp breaker is servicing the included distribution bus and therefore is not good for supplying one of the two 200-amp panels inside the basement.

Would it be better to just install a metered 400-amp panel that has only 2-200amp disconnects in it and then run a sub-panel from the interior 200-amp panels back to the outside of the home to allow for easier future electrical needs outside the home? (e.g. HP40SH )

The basement will be 95% finished upon completion of construction so future proofing future electrical needs on the outside of the home is very important.

I am also looking at having a Generac backup generator with a transfer switch installed to the main service panel.

Any guidance and advice would be greatly appreciated?

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  • What is driving the need for 400A service here? Also, how much stuff do you plan to put on the standby generator, and is transferring a single subpanel for standby loads acceptable (vs trying to do whole-house transfer)?
    – ThreePhaseEel
    Dec 6, 2018 at 0:19
  • Also, are you sure you need 2 furnaces and 2 A/Cs for a house that size? Modern construction practices re: insulation and air-sealing can get you to the point where the loads on a house that size are low enough that you can handle it with a single 3-4 ton A/C and matching heating system. Where are you putting this house, even, for that matter?
    – ThreePhaseEel
    Dec 6, 2018 at 1:04
  • @ThreePhaseEel We are building in an area that regularly reaches single digit temperatures at night during the colder months (October-April). We have spoken to several HVAC contractors about this and are not sold on 2 A/C's so most likely will be going with one 5-ton A/C, but the dual furnaces will help maintain comfortable temperatures (and smaller ducting) for kids in the basement, and my wife and I upstairs. As far as the backup generator goes I am only interested in running the refrigerator, some lights, maybe a TV and most importantly my network and servers (I work from home).
    – Ode
    Dec 6, 2018 at 5:45
  • Why generator for only that? I would go with a midsize solar battery system with a mains charger. Get LVDC supplies like Google does... No inverters, except for the fridge. That becomes the only power system for those house features, which makes the system quite simple...
    – Harper - Reinstate Monica
    Dec 6, 2018 at 20:00
  • Have you considered a hydronic-to-air system instead of conventional furnaces? Especially if you're considering heat pumps instead of conventional A/C, this would play nicer with both the heat pump side and the multi-zone side...
    – ThreePhaseEel
    Dec 8, 2018 at 17:33

1 Answer 1

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I have installed meter bases with limited service panels in the past, my last home I did what you want but you have to find the correct panel that can handle multiple 200 amp breakers. As far as the backup generator is it going to run the entire system or just one of the 200 amp subs? By setting up for one sub the cost will be much less as the transfer switches get really spendy for a 400 amp model.

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  • I would be looking for the generator to run one 200 Amp sub. Do you have a suggestion for the correct panel that would solve this issue?
    – Ode
    Dec 6, 2018 at 20:46
  • Not sure why the 2 down votes probably from the internet only electricians as this is an old question and I did not see the reply. Since you plan on doing the same thing as I have if you want a automated transfer switch I really like the cutter hammer 200 amp. If you want to do a MUCH cheaper method a mechanical interlock is the way I would suggest it’s easy when the panel is a main breaker type. I had a 400 amp service 200 went to my shop and 200 to the house at first it was all electric so I needed the large service. I had a mechanical interlock I installed in the house panel cheapest option
    – Ed Beal
    Sep 6, 2020 at 3:43

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